/Engine/Plugins/Runtime/XRBase/Source/XRBase/Public/MotionTrackedDeviceFunctionLibrary.h
Returns the system name used to distinguish the current tracking system. If no XR tracking system is active, then the name 'None' is returned.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="Input|MotionTracking") static [FName](API\Runtime\Core\UObject\FName) GetActiveTrackingSystemName()